FIELD OF THE INVENTION
The invention relates to a constant-current source with a MOSFET having a drain electrode connected to a first terminal of the current source and a source electrode and a control gate electrode connected to a second terminal of the current source.
Such a constant-current source is, for example, disclosed in a book entitled "Halbleiterschaltungstechnik" Semiconductor Circuit Technology! by Tietze and Schenk, 6th Edition, 1983, pages 94 and 95. In that case, use is made of a field-effect transistor of the depletion type, i.e. a normally-on field-effect transistor, as a result of which that current source can advantageously be used as a two-terminal network, since it is not necessary to apply an auxiliary voltage to the control gate. The production of such an auxiliary voltage would require additional circuitry.
However, a disadvantage of such a normally-on field-effect transistor is that it requires additional process steps in the case of conventional production processes for CMOS or BICMOS circuits.
U.S. Pat. No. 4,375,087 discloses an EEPROM storage cell which is formed with an n-channel MOS transistor equipped with a fully insulated gate that is disposed between the channel and the control gate and is in the floating state. Electrons are applied to the gate in order to program the cell, and are removed again upon erasure.